Flipping 'The Bird' Just Isn't Obscene Anymore, Law Professor Argues : The Two-Way"In the time of Caligula," says American University's Ira Robbins, "it was intended to be representative of a phallic symbol. Not today." Instead, showing a middle finger is an expression of "frustration or rage or anger or protest or disdain."

Much more from Audie's conversation with the professor will be on the show. Click here to find an NPR station that broadcasts or streams All Things Considered. We'll add the as-aired interview to the top of this post later.